/in/foo.cc: In function 'int main()':
/in/foo.cc:5:5: error: 'scanf' was not declared in this scope
     scanf("%d",&n);
     ^~~~~
/in/foo.cc:7:5: error: 'printf' was not declared in this scope
     printf("%d\n",k);
     ^~~~~~
/in/foo.cc:7:5: note: suggested alternative: 'int'
     printf("%d\n",k);
     ^~~~~~
     int